Field of the Invention
The present invention relates to an image processing apparatus and an image processing method, and specifically, to a technique that partially blurs an original image to generate a blurred image.
Description of the Background Art
In the technique described in Japanese Patent Application Laid-Open No. 2008-245033, a minimum-scale 2-dimensional wavelet coefficient about input image data is calculated. An in-focus state is regarded on coordinates having a wavelet coefficient equal to or larger than a predetermined threshold value, and the wavelet coefficient is kept. In contrast to this, with respect to coordinates having a wavelet coefficient smaller than the predetermined threshold value, a wavelet coefficient of each scale is multiplied by a control coefficient. Thereafter, inverse wavelet transformation is performed to obtain an output image. According to this, it is understood that, while the in-focus state of in-focus coordinates in an input image is kept, an image having a depth of field smaller than that of the input image is obtained.
The techniques described in Japanese Patent Application Laid-Open Nos. 2006-295299, 2006-203409, and 2002-94991 are related to compression encoding such as JPEG 2000 (Joint Photographic Experts Group 2000). In this compression encoding, a relatively larger code amount is allocated to a region of interest (ROI). According to this, it is understood that a pseudo focusing effect that complements a subject by focusing the subject and blurring a background is achieved.
As a method of developing the ROI of an image on a wavelet plane, a method employed in JPEG 2000 is known (see INTERNATIONAL STANDARD ISO/IEC 15444-1 ITU-T RECOMMENDATION T.800 Information technology-JPEG 2000 image coding system: Core coding system Annex H—Coding of images with regions of interest). A technique that determines a specific coefficient belonging to an ROI on a wavelet plane, though the type of the technique is different from that of the wavelet filter employed in JPEG 2000, is disclosed in Japanese Unexamined Patent Application Publication (Translation of PCT application) No. 2001-520466.
As techniques for separating a background from a foreground, a large number of techniques are developed. For example, the technique described in Japanese Patent Application Laid-Open No. 2011-34178 is given.
Various techniques are developed to generate a blurred image by partially blurring an original image.